Study On Inrush Current And Stead-State Operation Simulation Of The Scott Transformer With Secondary Midpoint Drawn-Out

Railway transportation plays an important role in China. With the growth of economy, there is a huge demand for development of railway construction. According to the eleventh five-year plan, by 2010 the total length of railway in China will increase to 95,000 km from 75,000 km at current time. In response to such great demand of railway construction, AT power supply mode is becoming the most effective method among all kinds of other ones because of its stronger power supply capability and less electromagnetic interference to surrounding environment.As a new thing, the Scott transformer with secondary midpoint drawn-out is integrated by traditional Scott transformer and single-phase connection type in AT power supply mode. The steady-state and transient state operations of the Scott transformer with secondary midpoint drawn-out are studied in this thesis. The primary content is listed as follow.The UMEC model of multi-winding transformer is built by he UMEC (Unified Magnetic Equivalent Circuit) model of single-phase double windings transformer. The voltage and current relationship of the primary side and the secondary side is simulated by the UMEC model of multi-winding transformer. The simulation result shows that the UMEC model of multi-winding transformer is proper and feasible. Based on the UMEC model of multi-winding transformer and the structural characteristics of the Scott transformer with secondary midpoint drawn-out, the UMEC model of the Scott transformer with secondary midpoint drawn-out is built. The voltage and current relationship matrix of the Scott transformer with secondary midpoint drawn-out is proposed in this thesis.Operation principle of the Scott transformer with secondary midpoint drawn-out is studied, including simulation research on two-phase decoupling and balance characteristics. Inrush current of the Scott transformer with secondary midpoint drawn-out is simulated by UMEC model of the Scott transformer with secondary midpoint drawn-out. The results show that the connection principle of current differential protection for the Scott transformer with secondary midpoint drawn-out is similar to the traditional Scott transformer.